Heat exchanger apparatus with spacer projections between plates

ABSTRACT

A heat exchanger apparatus is described in which the heat exchanger plates are spaced apart by spacer projections formed by indentations in such plates at positions intermediate to their longitudinal edges. The heat exchanger apparatus is of the counter-flow type so that two fluids flow in opposite directions through two channels on opposite sides of each heat exchanger plate. The exchanger plates have their ends split into two ends portions which are joined to two different exchanger plates on opposite sides thereof to form two separate sets of channels. A sealing means is provided along the longitudinal edges of the heat exchanger plates, including a synthetic plastic material bonded to such edges for sealing the channels. The spacer projections maintain the exchanger plates spaced apart by a fixed predetermined distance to enable a greater pressure difference between the two fluids flowing across each plate without changing the spacing between such plates.

Darm

HEAT EXCI-IANGER APPARATUS WITH SPACER PROJECTIONS BETWEEN PLATES Filed:

Inventor: William J. Darm, 5815 SW. Tucker Ave., Beaverton, Oreg. 97005Aug. 2, 1974 Appl. No.: 494,170

Related US. Application Data Continuation-in-part of'Ser. No. 468,659,May 10,

1974, which is a continuation of Ser. No. 221,543, Jan. 28, 1972,abandoned.

[52] US. Cl 165/166; 29/1573 [51] Int. Cl. F28F 3/10 [58] Field ofSearch l65/166.7, 4 F

[56] References Cited UNITED STATES PATENTS 1,816,757 7/1931 White165/166 X 1,826,344 10/1931 Dalgliesch 165/166 1,831,533 11/1931 Hubbard165/166 2,941,787 6/1960 Ramen..... 165/166 X 3,381,747 5/1968 Darn165/166 3,473,604 10/1969 Tiefenbache'r..... 165/166 3,719,227 11/1970Vensscn 165/166 R17,973 2/1931 Moshcr 165/161 1 Oct. 14, 1975 PrimaryExaminerCharles J. Myhre Assistant ExaminerTheophil W. Streule, Jr.Attorney, Agent, or Firm-Klarquist, Sparkman, Campbell, Leigh, Hall &Whinston A heat exchanger apparatus is described in which the heatexchanger plates are spaced apart by spacer projections formed byindentations in such plates at positions intermediate to theirlongitudinal edges. The heat exchanger apparatus is of the counter-flowtype so that two fluids flow in opposite directions through two channelson opposite sides of each heat exchanger plate. The exchanger plateshave their ends split into two ends portions which are joined to twodifferent exchanger plates on opposite sides thereof to form twoseparate sets of channels. A sealing means is provided along thelongitudinal edges of the heat exchanger plates, including a syntheticplastic material bonded to such edges for sealing the channels. Thespacer projections maintain the exchanger plates spaced apart by a fixedpredetermined distance to enable a greater pressure difference betweenthe two fluids flowing across each plate without changing the spacingbetween such plates.

ABSTRACT ll Claims, 5 Drawing Figures Sheet 1 of2 3,912,004

US. Patent Oct. 14, 1975 Sheet 2 0f 2 Oct. 14, 1975 US. Patent FIG. 3

HEAT EXCHANGER APPARATUS WITH SPACER PROJECTIONS BETWEEN PLATESREFERENCE TO RELATED PATENT APPLICATION BACKGROUND OF THE INVENTION Thepresent invention relates to heat exchanger apparatus used to exchangeheat between flowing streams of fluid, including liquid or gas, ofdifferent temperatures. In particular, the heat exchanger apparatusrelates to counter-flow type heat exchangers in which the two fluidsflow in opposite directions on opposite sides of metal heat exchangerplates, and the spacing between such plates is maintained at a fixed,predetermined distance by spacer projections formed by indentations inthe plates. These spacer projections are positioned intermediate to thetwo longitudinal edges of the exchanger plates and enable efficientoperation of the heat exchanger over a wide range of pressuredifferences between the two streams of liquid or gas flowingtherethrough. The heat exchanger apparatus of the present invention isparticularly adaptable for use as an air-to-air heat exchanger in abuilding ventilating system.

Counter-flow heat exchangers have been described in U.S. Pat. No.3,381,747 of W. J. Darm, including a plurality of separate heatexchanger plates disposed within a housing and defining two sets ofchannels with one channel of each set being provided on the oppositesides of a heat exchanger plate so that the two fluid streams flow inopposite directions to provide a very efficient heat exchangeroperation. In this prior apparatus, the heat exchanger plates are spacedapart by spacer strips positioned at the outer edges of the plates.However, this has the disadvantage that high pressure differencesbetween the two fluid streams cause the middle portions of the exchangerplates to bend toward and away from each other due to the pressuredifference, thereby changing the spacing between plates which results inless efficient operation. A less efficient cross-flow type of heatexchanger apparatus is shown in U.S. Pat. No. 3,473,604 of E.Tiefenbacher in which the two fluids flow perpendicular to each other onopposite sides of the heat exchanger plates. In this heat exchanger, theplates are undulated and are displaced from each other A the wave lengthof undulation and are spaced apart by terminal bars at their outer edgeswhich are soldered thereto at their opposite edges to form the channels.Neither of these prior heat exchangers is constructed in the simple,efficient manner of the present invention by which the heat exchangerplates have their ends split into two end portions which are joined todifferent heat exchanger plates on opposite sides thereof to form thetwo separate sets of channels. As a result, the heat exchanger apparatusof the present invention is simpler and less expensive to manufacture,and operates in a more efficient manner than previous heat exchangers.

SUMMARY OF THE INVENTION Therefore, it is one object of the presentinvention to provide an improved heat exchanger apparatus in which theheat exchanger plates are maintained in fixed predetermined spacedrelationship to enable its use with fluids which have a high pressuredifference and thereby provide a more efficient operation.

Another object of the invention is to provide such an improved heatexchanger apparatus in which the heat exchanger plates are spaced apartby a plurality of separate projections formed by indentations in theplates at intermediate positions between the two longitudinal edges ofthe plates in order to maintain the plate spacing at a fixed value.

A further object of the present invention is to provide such a heatexchanger apparatus which is of a counter- 7 flow type made of a simpleand inexpensive construction formed by splitting the ends of the heatexchanger plates into two end portions which are joined to differentheat exchanger plates on opposite sides thereof in order to form thetwosets of channels for the heat exchanger fluid, so that the two fluidscan flow in opposite directions on the opposite sides of a heatexchanger plate.

Still another object of the invention is to provide such a heatexchanger apparatus in which the channels are sealed by a layer ofsynthetic plastic sealing material bonded to the longitudinal edges ofthe heat exchanger plates and which may also bond the heat exchangerplates to the housing containing such plates.

BRIEF DESCRIPTION OF DRAWINGS Other objects and advantages of thepresent invention will become more apparent from the following detaileddescription of preferred embodiments thereof and from the attacheddrawings of which:

FIG. 1 is a perspective view showing an assembly of heat exchangerplates made in accordance with one embodiment of the invention prior tosealing such plates and mounting them in a housing;

FIG. 2 is a perspective view of a heat exchanger apparatus using a heatexchanger plate assembly similar to that of FIG. I with the heatexchanger housing broken away to show the internal construction of suchapparatus;

FIG. 3 is an enlarged horizontal section view taken along the line 33 ofFIG. 2;

FIG. 4 is a vertical section view taken along the line 44 of FIG. 3; and

FIG. 5 is a plan view of a portion of FIG. 2 shown on an enlarged scale.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS FIG. 1 shows an assembly10 of heat exchanger plates which may be employed in the heat exchangerapparatus of the present invention. The assembly 10 of heat exchangerplates is also referred to herein as a core element. The assembly 10includes a plurality of corrugated or undulated heat exchanger platesl2, l4, l6, l8 and 20 which are supported in the assembly in substantialparallelism in the intermediate portions thereof between their ends.Each of the heat exchanger plates is made of sheet metal, such asaluminum, and has a length conforming substantially to the length of theheat exchanger apparatus. The corrugations of the heat exchanger platesextend transversly to the length of the plates and therefore to the pathof the fluid transmitted through the heat exchanger so that suchcorrugations cause turbulence of such fluid which increases heatexchanging efficiency.

Each of the heat exchanger plates has both of its ends split into twoend portions by a cut 22 extending longitudinally partially down thelength of the plate. The two end portions of each split end of a heatexchanger plate are fastened to the end portions of different exchangerplates on opposite sides thereof by angle pieces 24 of U-shaped crosssections crimped thereto. The cut parallels the two longitudinal edges26 and 28 of the plate and normally is made about midway between suchlongitudinal edges in order to divide the ends of each plate into a pairof end portions or tongue segments. For example, the lower end of heatexchanger plate 12 is split into a pair of tongue segments 12a and 12bwhich are of approximately equal width.

The tongue segments of each exchanger plate end are shown bent inreversedirections. Thus tongue segment 12a, as shown in FIG. 1, is bentto curve outwardly (where it will meet with the housing of theexchangers which is assembled about the core element) and tongue segment12b below segment 12a is bent to curve inwardly. Considering exchangerplate 14, its upper tongue segment 14a is bent inwardly, whereas itslower tongue segment 14b is bent outwardly to meet tongue segment 1212.Where adjacent ends of tongue segments meet, they may be fixed togetherusing an overlying angle piece, such as angle piece 24, secured in placeas by crimping.

It will be noted that whereas the upper tongue segment 12a of plate 12is bent outwardly, and the lower one 12b is bent inwardly, at theopposite end of the exchanger plate the upper tongue segment 120 is bentinwardly whereas the lower one is bent outwardly. This same relationshipholds true for the tongue segments at each set of ends of an exchangerplate. A divider member shown at 30, including a horizontal wall expanse32 and a vertical marginal flange 34, may be inserted into cuts formingthe tongue segments, at each set of ends of the exchanger plates. Thedivider member, when positioned as shown in FIG. 1, serves to separateend portions of channels 36, 38, 40, 42, 44, 46 defined on opposite'sides of the various plates. Thus, and considering channel 40 in FIG. 1,the divider separates this channel where such is defined between tonguesegments 18a, 16a, from portions of channels 38 and 42 below thedivider, defined between tongue segments b, l8b and 16b, 14!),respectively.

As shown in FIG. 1, channels 36, 40 and 44 at the end of the assemblypictured at the bottom of FIG. 1, open to the end of the assembly abovethe divider. At the opposite end of the assembly, these channels open upto the end of the assembly below the divider. The reverse is true forchannels 38, 42 and 46 which at the end of the assembly pictured at thebottom of FIG. 1, open to the end of the assembly below the divider, andat the opposite end of the assembly, open to the end of the-assemblyabove the divider.

With the arrangement, and assuming the presence of an encompassingcasing, it should be obvious that one set of channels may be utilizedfor the passage of one body of fluid through the exchanger, and analternating set for the passage of another body of fluid through theexchanger, with such bodies of fluid passing through multiple flow pathsinterspersed with each other.

In making an exchanger with a core element of the type described, andwhen it is remembered that typically a far greater number of exchangerplates are utilized than actually pictured in FIG. 1, it should beobvious that a problem arises with respect to positioning properly theadjacent exchanger plates where they extend in expanses between the endsof the plates. The plates usually are made of thin metal, and ifcorrugated transversely of'their lengths, have considerable flexibilityin a transverse direction. Further, they are easily twisted. Obviously,if the plates are not properly oriented in the completed exchanger withsubstantially uniform spacing existing between them where they extendthroughout their length, the efficiency of the exchanger is affected.

Thus, according to this invention, the various exchanger plates arearranged substantially as pictured in FIG. 1. During assembly, and totie the various exchanger plates together, tying clips 48 which may bemetal strips attachable to the edges of the plates, are assembled withthe plates by fixedly attaching them to the edges of the plates atregions spaced along the length of the assembly. The clips are attachedto each of the opposite sets of adjacent edges in the plate assembly.The tying clip 48 specifically illustrated has slotted depressionsformed in it, the slots receiving edge portions of the plates, which maybe twisted slightly after being passed through the slots to hold theclip in place. The exchanger plates are also fastened together at theirends through joinder of the tongue segments with angle pieces 24.

As shown in FIG. 2, the heat exchanger apparatus of the presentinvention includes a plate assembly 10' similar to that of FIG. 1 whichis mounted within a sheet metal housing 50 having two sealing layers 52of epoxy resin or other suitable synthetic plastic material covering thetop and bottom portions of the housing. Each plastic sealing layer 52 isbonded to such housing and to the longitudinal edges of the heatexchanger plates, thereby sealing the channels between such heatexchanger plates and attaching such plates to the housing. If desired,the plastic sealing layers 52 may be provided with reinforcing sheets offiberglass material.

In addition to the tying clips 48', which hold the longitudinal edges ofthe heat exchanger plates in spaced relationship, two sets of spacerprojections 54 and 56 are at positions intermediate between thelongitudinal edges 26 and 28 thereof. The spacer projections may beformed by making indentations in the troughs or crests of the undulatedheat exchanger plates, such plates having their troughs and crests inalignment.

As shown in FIGS. 3 and 4, one set of spacer projections 54 is formed byprojections oflarger diameter and of greater height than the other setof spacer projections 56. Thus, the height 58 of projections 54 may bemany times the height 60 of projections 56. Projections 54 extend inwardtoward the longitudinal center line 62 of the heat exchanger plate,while projections 56 extend outwardly away from such center line. Forthis reason, the indentations forming the spacer projections 54 can bendthe sheet metal a greater distance than can the indentations formingprojections 56, without breaking such metal. For example, in order toprovide an optimum spacing between adjacent heat exchanger plates ofabout 7/16 of an inch, spacer projections 54 project a distance from theunbent undulated heat exchanger plates approximately three times theheight of projections 56 while the maximum diameter of projections 54 isabout twice the maximum diameter of projections 56. As shown in FIG. 4,the projections 54 and 56 are in the form of a plurality of separateconical projections having rounded peaks.

Each of the heat exchanger plates in FIG. 3 has projections 54 and 56extending from the opposite sides thereof into engagement withprojections on the two heat exchanger plates positioned on oppositesides of such one plate. In addition, it should be noted that the largeprojections 54 of one plate engage the small projections 56 on theadjacent plate and vice versa. In this manner, the spacing betweenadjacent heat exchanger plates is maintained as substantially fixedpredetermined distance regardless of the pressure of the fluids flowingthrough the chambers between such plates.

As shown in FIG. 2, it may be necessary to provide three horizontal rowsof spacer projections between the longitudinal edges 26 and 28 of theheat exchanger plates when such plates are extremely wide and theapparatus operates with a large difference in gas pressure between thetwo gas streams flowing on opposite sides of such plates. However, asingle horizontal row of spacer projections aligned with the divider 30may be employed on smaller widths of the exchanger plates.

As stated previously, the longitudinal edges of successive heatexchanger plates are spaced apart and tied to one another by means ofthe clips 48' which extend laterally across such longitudinal edges atthe top and bottom of the plates. As shown in FIG. 5 the clips 48' areslotted channel members which may be provided with a plurality of acuteangle slots 64 through a U- shaped channel portion formed in the bottomof such clips. The longitudinal edges of heat exchanger plates extendinto the slots 64 and are attached thereto by crimping 66 the portion ofsuch edges extending through the slots. In this manner, a rigid heatexchanger assembly is formed before it is enclosed in the metal housing50 and bonded thereto by the plastic sealing layer 52.

It will be obvious to those having ordinary skill in the art that manychanges may be made in the details of the above-described preferredembodiment of the present invention. For example, the heat exchangerplates may be flat rather than undulating and may be provided withspacer projections only on one side thereof which engage flat portionsof the adjacent heat exchanger plates. Therefore, the scope of thepresent invention should only be determined by the following claims.

I claim:

I. A counterflow heat exchanger apparatus comprisa plurality of heatexchanger plates defining a plurality of fluiid channels disposed sideby side between said plates, said plates having longitudinal edgesextending between the opposite ends thereof;

a plurality of fastening means for joining the opposite ends of theexchanger plates to the ends of other exchanger plates adjacent thereto,at least some of said plates having each of their ends split into twoend portions which are joined to two different exchanger plates onopposite sides thereof and separated by a divider member extendinglaterally to said end portions to form two separate sets of channelsboth of whose inlet and outlet openings are defined by said split endportions and said divider member, said two sets of channels bothextending in substantially the same direction, so that fluid can flowthrough one set in the opposite direction to fluid flowing through theother set of channels to provide a counterflow heat exchanger;

sealing means attached to the longitudinal edges of said plates forsealing said channels; and

spacer means for spacing the exchanger plates apart, said spacer meansincluding a plurality of separate spacer projections on the exchangerplates at intermediate positions between the two longitudinal edges ofthe plates, said projections on one plate extending into contact with atleast one other exchanger plate so that said one plate contacts the twoplates on opposite sides thereof to form each of said two sets ofchannels with fixed predetermined widths.

2. A heat exchanger apparatus in accordance with claim 1 in which thesealing means includes synthetic plastic material bonded to saidlongitudinal edges.

3. A heat exchanger apparatus in accordance with claim 2 which alsoincludes a housing containing said heat exchanger plates and bonded tosaid plastic material.

4. A heat exchanger apparatus in accordance with claim 1 in which theprojections extend outwardly from the opposite sides of the exchangerplate.

5. A heat exchanger apparatus in accordance with claim 4 in which theprojections of each plate engage projections of the two plates onopposite sides of said plate.

6. A heat exchanger apparatus in accordance with claim 1 in which theheat exchanger plates are undulated plates having undulated portionswith troughs and crests on opposite sides of a longitudinal center line,said two sets of channels both extending laterally across said troughsand crests, and said undulated plates being aligned with each other atsaid troughs and crests.

7. A heat exchanger apparatus in accordance with claim 6 in which theprojections include a plurality of first and second projections onopposite sides of the exchanger plates formed by indentations in thecrests or troughs, said first projections being formed by indentationsextending toward the longitudinal center line and said secondprojections being formed by indentations extending away from said centerline, and said first projections being of greater height than saidsecond projections.

8. A heat exchanger in accordance with claim 4 in which the projectionsare annular, substantially conical first and second projections onopposite sides of the exchanger, said first projections being of greaterheight and greater diameter than said second projections.

9. A heat exchanger apparatus in accordance with claim I in which thespacing means includes tying clips extending transversely across thelongitudinal edges of the heat exchanger plates and fixedly attachedthereto to space said edges apart.

10. A heat exchanger apparatus in accordance with claim 1 in which atleast some of the heat exchanger plates are undulated plates havingundulated portions providing troughs and crests on opposite sides of alongitudinal center line, and the spacer projections include projectionsformed by indentations in the undulated portions toward the center lineand which engage adjacent exchanger plates.

11. A heat exchanger apparatus in accordance with claim 10 in which theundulated plates are aligned with each other at said troughs and crests.

1. A counterflow heat exchanger apparatus comprising: a plurality ofheat exchanger plates defining a plurality of fluiid channels disposedside by side between said plates, said plates having longitudinal edgesextending between the opposite ends thereof; a plurality of fasteningmeans for joining the opposite ends of the exchanger plates to the endsof other exchanger plates adjacent thereto, at least some of said plateshaving each of their ends split into two end portions which are joinedto two different exchanger plates on opposite sides thereof andseparated by a divider member extending laterally to said end portionsto form two separate sets of channels both of whose inlet and outletopenings are defined by said split end portions and said divider member,said two sets of channels both extending in substantially the samedirection, so that fluid can flow through one set in the oppositedirection to fluid flowing through the other set of channels to providea counterflow heat exchanger; sealing means attached to the longitudinaledges of said plates for sealing said channels; and spacer means forspacing the exchanger plates apart, said spacer means including aplurality of separate spacer projections on the exchanger plates atintermediate positions between the two longitudinal edges of the plates,said projections on one plate extending into contact with at least oneother exchanger plate so that said one plate contacts the two plates onopposite sides thereof to form each of said two sets of channels withfixed predetermined widths.
 2. A heat exchanger apparatus in accordancewith claim 1 in which the sealing means includes synthetic plasticmaterial bonded to said longitudinal edges.
 3. A heat exchangerapparatus in accordance with claim 2 which also includes a housingcontaining said heat exchanger plates and bonded to said plasticmaterial.
 4. A heat exchanger apparatus in accordance with claim 1 inwhich the projections extend outwardly from the opposite sides of theexchanger plate.
 5. A heat exchanger apparatus in accordance with claim4 in which the projections of each plate engage pRojections of the twoplates on opposite sides of said plate.
 6. A heat exchanger apparatus inaccordance with claim 1 in which the heat exchanger plates are undulatedplates having undulated portions with troughs and crests on oppositesides of a longitudinal center line, said two sets of channels bothextending laterally across said troughs and crests, and said undulatedplates being aligned with each other at said troughs and crests.
 7. Aheat exchanger apparatus in accordance with claim 6 in which theprojections include a plurality of first and second projections onopposite sides of the exchanger plates formed by indentations in thecrests or troughs, said first projections being formed by indentationsextending toward the longitudinal center line and said secondprojections being formed by indentations extending away from said centerline, and said first projections being of greater height than saidsecond projections.
 8. A heat exchanger in accordance with claim 4 inwhich the projections are annular, substantially conical first andsecond projections on opposite sides of the exchanger, said firstprojections being of greater height and greater diameter than saidsecond projections.
 9. A heat exchanger apparatus in accordance withclaim 1 in which the spacing means includes tying clips extendingtransversely across the longitudinal edges of the heat exchanger platesand fixedly attached thereto to space said edges apart.
 10. A heatexchanger apparatus in accordance with claim 1 in which at least some ofthe heat exchanger plates are undulated plates having undulated portionsproviding troughs and crests on opposite sides of a longitudinal centerline, and the spacer projections include projections formed byindentations in the undulated portions toward the center line and whichengage adjacent exchanger plates.
 11. A heat exchanger apparatus inaccordance with claim 10 in which the undulated plates are aligned witheach other at said troughs and crests.